Upgrade to the recent prussdrv and some api enhancements

Owen, please review

1. recent prussdrv does not need a patch
2. included prussdrv sources for easy install
3. added setter/getter for PRU0 data ram
4. bumped up version

This was tested on the stock Angstrom, kernel 3.8.13, with node v0.8.22 (I used stock device tree fragment to initialize PRU: BB-BONE-PRU-01, as I do not need special pin assignments).

-Mike